Method and device for monitoring a bearing arrangement

ABSTRACT

A method and a device for monitoring a bearing arrangement, having at least one bearing, in a mounting element of a roller journal bearing of a roller in a stand of a rolling mill train are designed to initiate upkeep or repair work on the bearing arrangement at the correct time. The method involves measuring a process quantity at the bearing or in an area adjoining the bearing, providing an evaluation device with the measured value of the process quantity, comparing the measured value with a stored preset value, and triggering a signal as soon as the measured value exceeds or falls below the stored preset value.

This application is based on and claims priority under 35 U.S.C. §119with respect to German Application No. P 100 19 325.0 filed on Apr. 19,2000, the entire content of which is incorporated herein by reference.

FIELD OF THE INVENTION

The invention relates to bearing arrangements. More particularly, thepresent invention pertains to a device and method for monitoring abearing arrangement, having at least one bearing, in a mounting elementof a roller journal bearing of a roller (e.g., a support, intermediateor work roller) in a stand (e.g., a dual, quadruple or sextuple stand)of a rolling mill train.

BACKGROUND OF THE INVENTION

A rolling mill train, preferably for rolling out metallic material, isprimarily comprised of several roller frames, with the goods to bemilled being passed between at least two rollers. The rollers have ajournal at each of their two ends, and the journal is seated in aso-called mounting element. The mounting element represents the housingsupporting the roller, with a bearing arrangement being provided betweenthe roller journal and the mounting element.

The quality of the rolling process, as well as its efficiency, isgenerally determined by the ability of the bearing arrangement tofunction. It is necessary here to ensure that no bearing damage occursover time. This can be accomplished through use of preventivemaintenance at fixed intervals of time.

However, performing preventative maintenance at specified time intervalsinvariably results in the performance of preventive maintenance at timeswhen the bearing does not necessarily require such maintenance.

A need thus exists for a method and associated device for monitoring abearing arrangement of a support, intermediate or work roller in arolling mill train in a way that makes it possible to control theupkeep, maintenance and/or restoration of the bearing arrangement, aswell as its surroundings, in such a way that the upkeep, maintenanceand/or restoration is generally only actually triggered when there is areal need.

SUMMARY OF THE INVENTION

In accordance with one aspect of the invention, a method of monitoring abearing arrangement having at least one bearing in a mounting element ofa roller journal bearing involves measuring a process quantity at thebearing or in an area adjoining the bearing, providing an evaluationdevice with the measured value of the process quantity, comparing themeasured value with a stored preset value, and triggering a signal whenthe measured value exceeds or falls below the stored preset value.

The present invention is thus based on the discovery that a processquantity associated with a roller journal bearing in a roller in arolling mill train is characteristic of the roller journal bearing'sability to function, or of the operational dependability of the rollerjournal bearing. By monitoring or measuring the process quantity throughuse of a suitable sensor, the value of the process quantity can becompared, preferably on a permanent and ongoing or continual basis, witha maximum or minimum threshold value which has been stored in a memoryas a marginal threshold value required for the orderly operation of thebearing arrangement. Through comparison of the actual value with thenominal or threshold value, it is possible to trigger or initiate asignal when a permissible tolerance range is exceeded, thus providingthe operator of the rolling mill train with a warning that maintenanceor replacement work on the respective roller journal bearing, or itssurroundings, is necessary.

In accordance with one version of the present invention, the processquantity that is monitored is the force acting on the bearing. This caninclude the force acting in the axial direction of the bearing and/orthe force acting in the radial direction of the bearing. Various forcemeasuring bearings for measuring these forces are known in the art andused in other contexts. The stored threshold value for the maximumpossible bearing force would be of such a magnitude that a response ofthe monitoring system, i.e., the triggering of a signal, occurs if, forexample, forces act on the roller bearing reach an inadmissiblemagnitude. This could be due to, for example, wear in the vicinity ofthe bearing or could be due to other irregularities such as a tiltedroller positioning in the stand.

Further, as an alternative to monitoring the force acting on thebearing, or in addition to monitoring such force, the monitored processquantity can be the moisture in the bearing, or the moisture content ofthe lubricant in the bearing. It has been found that bearing damageoccurs if an inadmissibly high amount of moisture is contained in thebearing. It is thus possible through use of a moisture sensor to measureand monitor the moisture at suitable positions of the bearing or in thesurroundings of the bearing. The monitored or measured value of themoisture can then once again be compared to a stored threshold value sothat if the monitored or measured value exceeds the stored value, asignal or warning is issued indicating that maintenance or replacementwork on the respective roller journal bearing, or its surroundings, isrequired.

It is further possible as an alternative to, or in addition to,monitoring the force acting on the bearing and/or the moisture asdescribed above, to monitor or measure the temperature prevailing in thebearing. In this connection the temperature of the outer ring isprimarily considered because it can be measured in a relatively simplemanner.

As an alternative to or in addition to one or more of the processquantities mentioned above, the process quantity on which monitoring isbased can be the elastic or plastic deformation of the mounting element.In this case, the deformation can be maintained or measured in thecircumferential direction of the mounting element, which thus provides avalue indicating the ovalness of the mounting element, or can bemeasured in the axial direction of the mounting element. In the lattercase the cylindrical characteristics of the mounting element ismonitored. The deformation of the mounting element to be measured heretypically occurs in the form of a superimposition of elastic, and ofpossibly present plastic deformation. It has been found that whendefined threshold values of the deformation of the mounting element arereached, the service life of the bearing is clearly reduced. Thus,monitoring the deformation of the mounting element provides a reliableindication of a required repair or restoration of the mounting element.

As an alternative to or in addition to one or more of the processquantities mentioned above, the process quantity that is measured ormonitored can be the vibration amplitude and/or vibration frequency of apreset area of the bearing. It is also possible to measure or monitorthe vibration acceleration of a selected area of the bearing. Monitoringthe vibration property of a bearing, and preferably the statisticalevaluation thereof (amplitudes, frequencies, accelerations) can be usedas an indicator for deciding when it is necessary to service, orreplace, the bearing.

In accordance with the various aspects of the present inventiondescribed above, it is envisioned that the measured or monitored valuecan be transmitted in a wireless manner. In this regard, thetransmission can take place by infrared signals, induction or radiowaves.

According to another aspect of the invention, a device for monitoring abearing arrangement having at least one bearing in a mounting element ofa roller journal bearing includes at least one sensor which determines aprocess quantity at a bearing or in an area surrounding the bearing, amechanism for conducting the measured value of the process quantity toan evaluation device, a mechanism for comparing the measured value witha stored preset value, and a mechanism for triggering a signal wheneverthe measured value exceeds or falls below the stored preset value.

Depending on the type of parameter(s) to be monitored, a force sensor, amoisture sensor, a temperature sensor, a deformation sensor (preferablyin the form of one or several wire strain gauges) and/or a velocity oracceleration sensor, can be employed for monitoring the process quantityor parameter in question at the bearing.

Although not limited in this regard, the bearing is preferably a rollingbearing, a multi-row tapered roller bearing or a multi-row cylindricalroller bearing.

In accordance with a further development of the invention, the mechanismfor conducting the measured value of the process quantity to theevaluation device transmits the measured value in a wireless manner, forexample by induction or radio.

Thus, through implementation of the present invention, it is possible tomonitor various process quantities or parameters at a roller journalbearing of a roller in a rolling mill train, and to draw specificconclusions regarding when it is necessary to take measures forservicing or replacing the bearing. This makes it possible to initiatesuitable activities at the right moment for performing replacement ofthe bearing arrangement at the start of bearing damage. Optimization ofthe entire production process in the rolling mill train can thus berealized. The same applies to the mounting element (e.g., the housing)itself and the area surrounding the mounting element in the rollerstand. Here too it is possible by way of the described actions to assurethat a replacement part is installed at the right time. Wear in the areaof the roller journal bearing can be made relatively noticeable bymeasuring and monitoring the process quantities in question, and it canbe automatically indicated at the correct time that maintenance work isrequired. This means that an increased dependability with respect tounplanned outages can be realized, as well as the possibility ofdirectly identifying the source(s) of malfunctions.

According to another aspect of the invention, a stand in a rolling milltrain includes a plurality of rollers each provided with a rollerjournal, a bearing arrangement supporting the roller journal of at leastone roller and comprising at least one bearing, at least one sensorwhich monitors a value of a process quantity at the bearing or in anarea surrounding the bearing, a comparing device that compares themeasured value of the process quantity with a stored preset value, and adevice for triggering a signal when the measured value exceeds or fallsbelow the stored preset value.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

The foregoing and additional features and characteristics of the presentinvention will become more apparent from the following detaileddescription considered with reference to the accompanying drawingfigures in which like reference numerals designate like elements andwherein:

FIG. 1 is a schematic cross sectional view of a sextuple stand of arolling mill train;

FIG. 2 is a cross-sectional view of a roller journal bearing and variouselements used for monitoring; and

FIG. 3 is a cross-sectional view similar to FIG. 2 illustrating amulti-row tapered roller bearing embodying the present invention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 illustrates a sextuple stand 11 in a rolling mill train forrolling a material 12 that is to be milled. The material 12 to be milledis transported in the direction of the leftward directed arrow. Thestand 11 has a total of six rollers or work rollers 8, 9, 10 which rolloff on each other, or on the material 12 to be milled. In theillustrated embodiment, the work rollers 10 which engage and roll thematerial 12 are in contact with the intermediate rollers 9, which inturn work together with the support rollers 8.

FIG. 2 shows the end of one of the rollers 8, 9, 10 with its associatedroller journal 7. The roller journal 7 is seated in a mounting element 6which is in the form of a housing. A bearing arrangement 1 is providedfor seating. In the illustrated version, the bearing arrangement 1 is abearing with four bearing rows 2, 3, 4, 5.

As illustrated in FIG. 2, a sensor 14 is integrated into the bearingarrangement 1 and/or the mounting element 6 at a suitable location. Thesensor can be in one of several forms, depending upon the processquantity(s) or parameter(s) to be measured or monitored. One possibilityis a force sensor. Here, a force-measuring bearing can be equipped witha force sensor. It is also possible, as an alternative to or in additionto the force sensor, to integrate moisture and/or temperature sensorsinto the bearing. In the same way it is also possible, as an alternativeto or in addition to one or more of the sensors mentioned above, todetect the deformation of the bearing arrangement by an appropriatearrangement and connection of wire strain gauges. Finally, accelerationor distance sensors can be integrated into the bearing for recordingvibrations, once again as an alternative to or in addition to one ormore of the various sensors mentioned above. It is thus envisioned thatthe various sensors mentioned above can be used individually or can beemployed in any desired combinations, depending upon the processquantities or parameters to be measured. Suitable sensors to be employedin the present invention for measuring or monitoring the processquantities or parameters mentioned above are known in the art and arethus not described in detail here.

The sensor 14 conducts or sends a value indicative of the detectedprocess quantity or parameter W to an evaluation device 13. Appropriatemechanisms 15 for conducting the measured or detected value are employedfor this purpose. The dashed arrow in FIG. 2 indicates that thetransmission of the value of the process quantity W can also take placein a wireless manner, for example by radio waves, infrared signals, orinduction.

In addition to the measured value of the process quantity W, theevaluation device 13 also receives a stored preset value W_(max/min)that is related to the measured or detected process quantity. A suitablecomparator 16 forming a comparing device compares the measured value Wwith the preset value W_(max/min) and determines whether the measuredvalue W (actual value) is within the permissible tolerance range(nominal value). That is, the comparator 16 determines whether themeasured value W is less than a permissible maximum value, or is greaterthan a permissible minimum value. In most cases, the measured value willbe compared with a preset maximum value for force, moisture, temperatureor deformation as the maximum value will likely be of most importance.

If the preset tolerance range, or the preset minimum/maximum value, forthe measured process quantity is exceeded, a mechanism 17 causes thetriggering or output of a signal. This can take place in a variety ofdifferent ways, for example by indicator lights or by acousticalsignals. The signal informs or notifies the operator(s) of the rollingmill train that permissible operating parameters have been exceeded.With this information, it is then possible to initiate maintenance workat the bearing to avoid loss of the bearing.

As mentioned above, one possible sensor which can be employed in thepresent invention is a suitable force sensor for measuring or monitoringthe force acting on the bearing. The force to be measured or monitoredcan be the force acting in the bearing axial direction and/or the forceacting in the bearing radial direction. The stored threshold value forthe maximum possible bearing force would be of such a magnitude that aresponse of the monitoring system, i.e., the triggering of a signal,occurs if, for example, forces act on the roller bearing reach aninadmissible magnitude. This could be due to, for example, wear in thevicinity of the bearing or could be due to other irregularities such asa tilted roller positioning in the stand.

As mentioned above, the sensor can also be selected to measure ormonitor the moisture in the bearing, or the moisture content of thelubricant in the bearing. Experience has shown that bearing damage canoccur if an inadmissibly high amount of moisture is contained in thebearing. A suitable moisture sensor can thus be used to measure andmonitor the moisture at suitable positions of the bearing or in thesurroundings of the bearing. The monitored or measured value of themoisture is then compared to a stored threshold value so that if themonitored or measured value exceeds the stored value, a signal orwarning is issued indicating that maintenance or replacement work on therespective roller journal bearing, or its surroundings, is required.

As mentioned above, a further type of sensor which can be employed inthe present invention involves a sensor for measuring or monitoring thetemperature prevailing in the bearing. The temperature of the outer ringis one preferred area of temperature measurement because the outer ringtemperature can be measured in a relatively simple manner.

A further type of sensor mentioned above is a sensor that measures ormonitors the elastic or plastic deformation of the mounting element. Thedeformation can be measured in the circumferential direction of themounting element to thus provide a value indicating the ovalness of themounting element, or can be measured in the axial direction of themounting element to provide a value indicating the axial or cylindricalcharacteristics of the mounting element. The deformation of the mountingelement to be measured here typically occurs in the form of asuperimposition of elastic, and possibly present plastic deformation.Experience has shown that when defined threshold values of thedeformation of the mounting element are reached, the service life of thebearing is reduced. Thus, monitoring the deformation of the mountingelement provides a reliable indication that a repair or restoration ofthe mounting element is required.

Another type of sensor which can be employed is one that measures ormonitors the vibration amplitude and/or vibration frequency of a presetarea of the bearing. It is also possible to monitor the vibrationacceleration of a selected area of the bearing. Monitoring or measuringthe vibration property of a bearing, including the statisticalevaluation of the vibration property (amplitudes, frequencies,accelerations) can be used to indicate when it is necessary to serviceor replace the bearing.

The present invention is described and illustrated in the context of aroller having a journal at its end, as is often the case, which isseated by way of the bearing arrangement. However, as an alternative,the roller can be provided with an interior bore in both of its endareas, into each of which a journal projects, which is attached to thehousing. In this alternative, the bearing would arranged between thisjournal and the cylindrical interior face of the bore.

The present invention provides a method and device for measuring ormonitoring one or more process quantities or parameters associated witha roller journal bearing in a roller in a rolling mill train, preferablythrough use of one or more appropriate sensors. These processquantity(s) or parameter(s) are indicative of the functioning of theroller journal bearing, or the operational dependability of the rollerjournal bearing. The value of the measured or monitored process quantitycan then be compared with a maximum or minimum threshold value stored ina memory as the marginal threshold value required for the orderly orproper operation of the bearing arrangement. Through comparison of theactual value and the nominal or threshold value, it is possible toinitiate a signal when a permissible tolerance range is exceeded, thusproviding the operator of the rolling mill train with a warning thatmaintenance or replacement work on the respective roller journalbearing, or its surroundings, is required.

It is to be understood from the illustration in FIG. 2 that the methodand device of the present invention for measuring and monitoring abearing arrangement is applicable to the support roller, theintermediate roller and/or the work roller of the sextuple stand of therolling mill train. The present invention is also applicable to dual orquadruple stands of a rolling mill train. Also, the bearing can be arolling bearing, a multi-row tapered roller bearing as shown in FIG. 3or a multi-row cylindrical roller bearing as shown in FIG. 2.

The principles, preferred embodiments and modes of operation of thepresent invention have been described in the foregoing specification.However, the invention which is intended to be protected is not to beconstrued as limited to the particular embodiments disclosed. Further,the embodiments described herein are to be regarded as illustrativerather than restrictive. Variations and changes may be made by others,and equivalents employed, without departing from the spirit of thepresent invention. Accordingly, it is expressly intended that all suchvariations, changes and equivalents which fall within the spirit andscope of the present invention as defined in the claims, be embracedthereby.

What is claimed is:
 1. A method for monitoring a bearing arrangement ina stand in a rolling mill train that mills metal, the stand including aplurality of rollers, at least one of the rollers provided with a rollerjournal seated in a mounting element by way of said bearing arrangement,the bearing arrangement having at least one bearing, the methodcomprising: measuring a value of a process quantity at the bearing orthe mounting element by way of a sensor mounted in the bearingarrangement or the mounting element; providing the measured value of theprocess quantity to an evaluation device; comparing the measured valueof the process quantity with a stored preset value; and triggering asignal when the measured value of the process quantity exceeds or fallsbelow the stored preset value.
 2. The method in accordance with claim 1,wherein the measurement of the value of the process quantity includesmeasuring a force acting on the bearing.
 3. The method in accordancewith claim 2, wherein the force acting on the bearing is the forceacting in an axial direction of the bearing.
 4. The method in accordancewith claim 2, wherein the force acting on the bearing is the forceacting in the radial direction of the bearing.
 5. The method inaccordance with claim 1, wherein the measurement of the value of theprocess quantity includes measuring moisture present in the bearing ormeasuring moisture content of lubricant for the bearing.
 6. The methodin accordance with claim 1, wherein the measurement of the value of theprocess quantity includes measuring a temperature prevailing in thebearing.
 7. The method in accordance with claim 1, wherein themeasurement of the value of the process quantity includes measuring atemperature prevailing in an outer ring of the bearing.
 8. The method inaccordance with claim 1, wherein the measurement of the value of theprocess quantity includes measuring at least one of an elasticdeformation of the mounting element and a plastic deformation of themounting element.
 9. The method in accordance with claim 8, wherein thedeformation of the mounting element is measured in a circumferentialdirection of the mounting element.
 10. The method in accordance withclaim 8, wherein the deformation of the mounting element is measured inan axial direction of the mounting element.
 11. The method in accordancewith claim 1, wherein the measurement of the value of the processquantity includes measuring at least one of a vibration amplitude of apreset area of the bearing and a vibration frequency of a preset area ofthe bearing.
 12. The method in accordance with claim 1, wherein themeasurement of the value of the process quantity includes measuring avibration acceleration of a preset area of the bearing.
 13. The methodin accordance with claim 1, wherein the measured value is transmitted ina wireless manner.
 14. The method in accordance with claim 13, whereinthe wireless transmission takes place by way of infrared signals. 15.The method in accordance with claim 13, wherein the wirelesstransmission takes place by way of radio waves.
 16. A rolling mill trainwhich mills metal, comprising: a stand comprised of a plurality ofrollers, at least one of the rollers being provided a roller journalseated in a mounting element by way of a bearing arrangement thatincludes a bearing; at least one sensor mounted in the bearingarrangement or the mounting element which monitors a value of a processquantity at the bearing or the mounting element; conducting means forconducting the monitored value of the process quantity from the at leastone sensor; comparing means for comparing the monitored value of theprocess quantity with a stored preset value; and means for triggering asignal when the monitored value exceeds or falls below the stored presetvalue.
 17. The device in accordance with claim 16, wherein the sensor isa force sensor.
 18. The device in accordance with claim 16, wherein thesensor is a moisture sensor.
 19. The device in accordance with claim 16,wherein the sensor is a temperature sensor.
 20. The device in accordancewith claim 16, wherein the sensor is a deformation sensor.
 21. Thedevice in accordance with claim 16, wherein the sensor is a wire straingauge.
 22. The device in accordance with claim 16, wherein the sensor isa velocity sensor or acceleration sensor.
 23. The device in accordancewith claim 16, wherein the bearing is a rolling bearing.
 24. The devicein accordance with claim 16, wherein the bearing is a multi-row taperedroller bearing.
 25. The device in accordance with claim 16, wherein thebearing is a multi-row tapered roller bearing.
 26. The device inaccordance with claim 16, wherein the bearing is a multi-row cylindricalroller bearing.
 27. The device in accordance with claim 16, wherein theconducting means transmits the monitored value of the process quantityin a wireless manner.